There are also "active" extension cables that are a 5 meter cable with a 1 port hub built into the far end.

I've heard as many as 5 can be chained together to go farther. Latency starts to become an issue, and many USB drivers do not handle the distance well. It works well enough for remote keyboards and mice.

and how did you get cables this long? Only 5mts cables are on sale on Amazon
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Eduardo MolteniJun 3 '09 at 12:19

This sounds like it should be the punchline for a bad joke... but "join 2 together"? :) Just used 2 consecutive extenders (plus the length of keyboard cable it may have been up to 9m)
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Tom NewtonJun 4 '09 at 7:13